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Five different land use types (desert, farmland, mining park, slag heap and tailing dam) were selected as variables around the Jinchuan Cu-Ni mining area in Jinchang, Gansu Province in the present study. The Atriplex canescens (Pursh) Nutt.’s rhizosphere bacterial abundance, diversity and community composition were examined taking advantage of High-throughput sequencing technology to discuss the effect of soil physicochemical properties on soil microbial community structure. The result indicated that the phylum Proteobacteria and Firmicutes was the most dominant taxon in desert, farmland and mining park, with a high abundance more than 30%. The phylum Proteobacteria was the most dominant taxon in slag heap and tailing dam, with a high abundance more than 40%. The tailing dam had the highest bacterial Chao indexes and the farmland had the highest bacterial Observed species indexes, Shannon indexes and Simpson indexes. Observed species indexes and Shannon indexes between the five sites were significantly different. The redundancy analysis and principal component analysis showed that the main environmental factors caused the different of rhizosphere bacterial community structure in five land use types were Mg, Ca, Cu, TN and moisture, followed by Ni, Cr, K, Pb, Zn content and pH. Hence, the result indicates that land use and soil environmental factors had significant impact on the diversity of soil microbial community structure.

The present work was aimed to study the effect of melatonin pre-treatments on oxidative stress modulation, cadmium (Cd) accumulation, and tolerance in Abutilon theophrasti Medicus under the hydroponic system. Application of substances that can modulate the harmful effects of Cd on plant yield and reduce its accumulation in the edible parts is of particular importance. Therefore, the Abutilon pre-treated with 0.1mM melatonin were exposed to 200μM, 400μM, 800μM Cd. Our results showed that 0.1mM melatonin led to positive effects on 200μM and 400μM Cd tolerance, including a significant increase in root activity andperoxidase (POD) activity and a significant decrease in malondialdehyde (MDA) content. Withthe help of melatonin, the enrichment factor (BCF) significantly decreased, reducing the content in the ground and roots. At least in our experiment conditions, this information appears to be useful for healthy food production.

Plants from different functional groups show distinct response to nitrogen (N) addition, however, the patterns and underlying mechanisms across the natural N availability gradient remain unexplored. In present studies, effects of soil N fertility on aboveground N pools and production were examined, and the N: P stoichiometry was compared among forbs, graminoids, and legumes on an alpine grassland located in northeast of Qinghai-Tibet Plateau. Mean N: P ratios of the whole community in 2008 and 2009 were 9. 83 and 11.57, respectively, indicating that the sub-alpine grassland was mainly N-limited. The partial redundancy analysis (partial RDA) showed that the biomass percentage of forbs increased, while those of legumes and graminoids decreased with the soil N availability. It suggested that legumes and graminoids were more competitive than forbs in the natural N-limited grassland, which may be due to the N2-fixation ability and high nutrient use efficiency, respectively. Under the projected increasing N deposition, the vegetation tended to shift from graminoids and legumes to forbs. Significant relationships were found between the percentage of legumes biomass and N: P (phosphorus) ratio for the whole community and non-legumes, indicating that legumes could improve the community N status as well as non-legumes N status on the alpine grassland.